Acquiring RPM

The best way to get RPM is to install Red Hat Linux. If you don't want to do that, you can still get and use RPM. It can be acquired from ftp.redhat.com.

RPM Requirements

RPM itself should build on basically any Unix-like system. It has been built and used on Tru64 Unix, AIX, Solaris, SunOS, and basically all flavors of Linux.

To build RPMs from source, you also need everything normally required to build a package, like gcc, make, etc.

The Spec File

We'll begin with discussion of the spec file. Spec files are required to build a package. The spec file is a description of the software along with instructions on how to build it and a file list for all the binaries that get installed.

You'll want to name your spec file according to a standard convention. It should be the package name-dash-version number-dash-release number-dot-spec. This will ensure that if you install multiple source RPMs for different versions of the same package that at least the spec files remain intact.

Here is a small spec file (eject-2.0.2-1.spec):

Summary: A program that ejects removable media using software control.
Name: eject
Version: 2.0.2
Release: 3
Copyright: GPL
Group: System Environment/Base
Source: http://metalab.unc.edu/pub/Linux/utils/disk-management/eject-2.0.2.tar.gz
Patch: eject-2.0.2-buildroot.patch
BuildRoot: /var/tmp/%{name}-buildroot

%description
The eject program allows the user to eject removable media
(typically CD-ROMs, floppy disks or Iomega Jaz or Zip disks)
using software control. Eject can also control some multi-
disk CD changers and even some devices' auto-eject features.

Install eject if you'd like to eject removable media using
software control.

%prep
%setup -q
%patch -p1 -b .buildroot

%build
make RPM_OPT_FLAGS="$RPM_OPT_FLAGS"

%install
rm -rf $RPM_BUILD_ROOT
mkdir -p $RPM_BUILD_ROOT/usr/bin
mkdir -p $RPM_BUILD_ROOT/usr/man/man1

install -s -m 755 eject $RPM_BUILD_ROOT/usr/bin/eject
install -m 644 eject.1 $RPM_BUILD_ROOT/usr/man/man1/eject.1

%clean
rm -rf $RPM_BUILD_ROOT

%files
%defattr(-,root,root)
%doc README TODO COPYING ChangeLog

/usr/bin/eject
/usr/man/man1/eject.1

%changelog
* Sun Mar 21 1999 Cristian Gafton <gafton@redhat.com> 
- auto rebuild in the new build environment (release 3)

* Wed Feb 24 1999 Preston Brown <pbrown@redhat.com> 
- Injected new description and group.

[ Some changelog entries trimmed for brevity.  -Editor. ]
      

The Header

The header has some standard fields in it that you need to fill in. There are a few caveats as well. The fields must be filled in as follows:

• Summary: This is a one line description of the package.

• Name: This must be the name string from the rpm filename you plan to use.

• Version: This must be the version string from the rpm filename you plan to use.

• Release: This is the release number for a package of the same version (ie. if we make a package and find it to be slightly broken and need to make it again, the next package would be release number 2).

• Copyright: This line tells how a package is copyrighted. You should use something like GPL, BSD, MIT, public domain, distributable, or commercial.

• Group: This is a group that the package belongs to in a higher level package tool or the Red Hat installer.

• Source: This line points at the HOME location of the pristine source file. It is used if you ever want to get the source again or check for newer versions. Caveat: The filename in this line MUST match the filename you have on your own system (ie. don't download the source file and change its name). You can also specify more than one source file using lines like:

  Source0: blah-0.tar.gz Source1: blah-1.tar.gz Source2: fooblah.tar.gz

  These files would go in the SOURCES directory. (The directory structure is discussed in a later section, "The Source Directory Tree".)

• Patch: This is the place you can find the patch if you need to download it again. Caveat: The filename here must match the one you use when you make YOUR patch. You may also want to note that you can have multiple patch files much as you can have multiple sources. ] You would have something like:

  Patch0: blah-0.patch Patch1: blah-1.patch Patch2: fooblah.patch

  These files would go in the SOURCES directory.

• Group: This line is used to tell high level installation programs (such as Red Hat's gnorpm) where to place this particular program in its hierarchical structure. You can find the latest description in /usr/doc/rpm*/GROUPS. The group tree currently looks something like this:

  Amusements/Games Amusements/Graphics Applications/Archiving Applications/Communications Applications/Databases Applications/Editors Applications/Emulators Applications/Engineering Applications/File Applications/Internet Applications/Multimedia Applications/Productivity Applications/Publishing Applications/System Applications/Text Development/Debuggers Development/Languages Development/Libraries Development/System Development/Tools Documentation System Environment/Base System Environment/Daemons System Environment/Kernel System Environment/Libraries System Environment/Shells User Interface/Desktops User Interface/X User Interface/X Hardware Support

• BuildRoot: This line allows you to specify a directory as the "root" for building and installing the new package. You can use this to help test your package before having it installed on your machine.

• %description It's not really a header item, but should be described with the rest of the header. You need one description tag per package and/or subpackage. This is a multi-line field that should be used to give a comprehensive description of the package.

Prep

This is the second section in the spec file. It is used to get the sources ready to build. Here you need to do anything necessary to get the sources patched and setup like they need to be setup to do a make.

One thing to note: Each of these sections is really just a place to execute shell scripts. You could simply make an sh script and put it after the %prep tag to unpack and patch your sources. We have made macros to aid in this, however.

The first of these macros is the %setup macro. In its simplest form (no command line options), it simply unpacks the sources and cd's into the source directory. It also takes the following options:

• -n name will set the name of the build directory to the listed name. The default is $NAME-$VERSION. Other possibilities include $NAME, ${NAME}${VERSION}, or whatever the main tar file uses. (Please note that these "$" variables are not real variables available within the spec file. They are really just used here in place of a sample name. You need to use the real name and version in your package, not a variable.)

• -c will create and cd to the named directory before doing the untar.

• -b # will untar Source# before cd'ing into the directory (and this makes no sense with -c so don't do it). This is only useful with multiple source files.

• -a # will untar Source# after cd'ing into the directory.

• -T This option overrides the default action of untarring the Source and requires a -b 0 or -a 0 to get the main source file untarred. You need this when there are secondary sources.

• -D Do not delete the directory before unpacking. This is only useful where you have more than one setup macro. It should only be used in setup macros after the first one (but never in the first one).

The next of the available macros is the %patch macro. This macro helps automate the process of applying patches to the sources. It takes several options, listed below:

• # will apply Patch# as the patch file.

• -p # specifies the number of directories to strip for the patch(1) command.

• -P The default action is to apply Patch (or Patch0). This flag inhibits the default action and will require a 0 to get the main source file untarred. This option is useful in a second (or later) %patch macro that required a different number than the first macro.

• You can also do %patch# instead of doing the real command: %patch # -P

• -b extension will save originals as filename.extension before patching.

That should be all the macros you need. After you have those right, you can also do any other setup you need to do via sh type scripting. Anything you include up until the %build macro (discussed in the next section) is executed via sh. Look at the example above for the types of things you might want to do here.

Build

There aren't really any macros for this section. You should just put any commands here that you would need to use to build the software once you had untarred the source, patched it, and cd'ed into the directory. This is just another set of commands passed to sh, so any legal sh commands can go here (including comments).

The variable RPM_OPT_FLAGS is set using values in /usr/lib/rpm/rpmrc. Look there to make sure you are using values appropriate for your system (in most cases you are). Or simply don't use this variable in your spec file. It is optional.

Install

There aren't really any macros here, either. You basically just want to put whatever commands here that are necessary to install. If you have make install available to you in the package you are building, put that here. If not, you can either patch the makefile for a make install and just do a make install here, or you can hand install them here with sh commands. You can consider your current directory to be the toplevel of the source directory.

The variable RPM_BUILD_ROOT is available to tell you the path set as the Buildroot: in the header. Using build roots are optional but are highly recommended because they keep you from cluttering your system with software that isn't in your RPM database (building an RPM doesn't touch your database...you must go install the binary RPM you just built to do that).

Cleaning your system

It's a good idea to always make sure there is a clean build root before building a package a second time on a system. The %clean macro will help with that. Simply put the proper commands there to blow away a former build root. Anal, err, careful folks may want to test that RPM_BUILD_ROOT wasn't set to / before doing something this volatile.

Optional pre and post Install/Uninstall Scripts

You can put scripts in that get run before and after the installation and uninstallation of binary packages. A main reason for this is to do things like run ldconfig after installing or removing packages that contain shared libraries. The macros for each of the scripts is as follows:

• %pre is the macro to do pre-install scripts.

• %post is the macro to do post-install scripts.

• %preun is the macro to do pre-uninstall scripts.

• %postun is the macro to do post-uninstall scripts.

The contents of these sections should just be any sh style script, though you do not need the #!/bin/sh.

Files

This is the section where you must list the files for the binary package. RPM has no way to know what binaries get installed as a result of make install. There is NO way to do this. Some have suggested doing a find before and after the package install. With a multiuser system, this is unacceptable as other files may be created during a package building process that have nothing to do with the package itself.

There are some macros available to do some special things as well. They are listed and described here:

• %doc is used to mark documentation in the source package that you want installed in a binary install. The documents will be installed in /usr/doc/$NAME-$VERSION-$RELEASE. You can list multiple documents on the command line with this macro, or you can list them all separately using a macro for each of them.

• %config is used to mark configuration files in a package. This includes files like sendmail.cf, passwd, etc. If you later uninstall a package containing config files, any unchanged files will be removed and any changed files will get moved to their old name with a .rpmsave appended to the filename. You can list multiple files with this macro as well.

• %dir marks a single directory in a file list to be included as being owned by a package. By default, if you list a directory name WITHOUT a %dir macro, EVERYTHING in that directory is included in the file list and later installed as part of that package.

• %defattr allows you to set default attributes for files listed after the defattr declaration. The attributes are listed in the form (mode, owner, group) where the mode is the octal number representing the bit pattern for the new permissions (like chmod would use), owner is the username of the owner, and group is the group you would like assigned. You may leave any field to the installed default by simply placing a - in its place, as was done in the mode field for the example package.

• %files -f <filename> will allow you to list your files in some arbitrary file within the build directory of the sources. This is nice in cases where you have a package that can build it's own filelist. You then just include that filelist here and you don't have to specifically list the files.

The biggest caveat in the file list is listing directories. If you list /usr/bin by accident, your binary package will contain every file in /usr/bin on your system.

Changelog

This is a log of what changes occurred when the package is updated. If you are modifying an existing RPM it is a good idea to list what changes you made here.

The format is simple. Start each new entry with a line with a * followed by the date, your name, and your email address. The date should appear in the same format that is output by:

	date +"%a %b %d %Y"
      

The rest of the section is a free text field, but should be organized in some coherent manner.

The Source Directory Tree

The first thing you need is a properly configured build tree. This is configurable using the /etc/rpmrc file. Most people will just use /usr/src.

You may need to create the following directories to make a build tree:

• BUILD is the directory where all building occurs by RPM. You don't have to do your test building anywhere in particular, but this is where RPM will do it's building.

• SOURCES is the directory where you should put your original source tar files and your patches. This is where RPM will look by default.

• SPECS is the directory where all spec files should go.

• RPMS is where RPM will put all binary RPMs when built.

• SRPMS is where all source RPMs will be put.

Test Building

The first thing you'll probably want to to is get the source to build cleanly without using RPM. To do this, unpack the sources, and change the directory name to $NAME.orig. Then unpack the source again. Use this source to build from. Go into the source directory and follow the instructions to build it. If you have to edit things, you'll need a patch. Once you get it to build, clean the source directory. Make sure and remove any files that get made from a configure script. Then cd back out of the source directory to its parent. Then you'll do something like:

diff -uNr dirname.orig dirname > ../SOURCES/dirname-linux.patch
      

This will create a patch for you that you can use in your spec file. Note that the "linux" that you see in the patch name is just an identifier. You might want to use something more descriptive like "config" or "bugs" to describe why you had to make a patch. It's also a good idea to look at the patch file you are creating before using it to make sure no binaries were included by accident.

Generating the File List

Now that you have source that will build and you know how to do it, build it and install it. Look at the output of the install sequence and build your file list from that to use in the spec file. We usually build the spec file in parallel with all of these steps. You can create the initial one and fill in the easy parts, and then fill in the other steps as you go.

Building the Package with RPM

Once you have a spec file, you are ready to try and build your package. The most useful way to do it is with a command like the following:

rpm -ba foobar-1.0.spec
      

There are other options useful with the -b switch as well:

• p means just run the prep section of the specfile.

• l is a list check that does some checks on %files.

• c do a prep and compile. This is useful when you are unsure of whether your source will build at all. It seems useless because you might want to just keep playing with the source itself until it builds and then start using RPM, but once you become accustomed to using RPM you will find instances when you will use it.

• ido a prep, compile, and install.

• b prep, compile, install, and build a binary package only.

• abuild it all (both source and binary packages).

There are several modifiers to the -b switch. They are as follows:

• --short-circuit will skip straight to a specified stage (can only be used with c and i).

• --clean removes the build tree when done.

• --keep-temps will keep all the temp files and scripts that were made in /tmp. You can actually see what files were created in /tmp using the -v option.

• --test does not execute any real stages, but does keep-temp.

Testing It

Once you have a source and binary rpm for your package, you need to test it. The easiest and best way is to use a totally different machine from the one you are building on to test. After all, you've just done a lot of make install's on your own machine, so it should be installed fairly well.

You can do an rpm -e packagename on the package to test, but that can be deceiving because in building the package, you did a make install. If you left something out of your file list, it will not get uninstalled. You'll then reinstall the binary package and your system will be complete again, but your rpm still isn't. Make sure and keep in mind that just because you do a rpm -ba package, most people installing your package will just be doing the rpm -i package. Make sure you don't do anything in the build or install sections that will need to be done when the binaries are installed by themselves.

What to do with your new RPMs

Once you've made your own RPM of something (assuming its something that hasn't already been RPM'ed), you can contribute your work to others (also assuming you RPM'ed something freely distributable). To do so, you'll want to upload it to ftp.redhat.com.

What Now?

Please see the above sections on Testing and What to do with new RPMs. We want all the RPMs available we can get, and we want them to be good RPMs. Please take the time to test them well, and then take the time to upload them for everyone's benefit. Also, please make sure you are only uploading freely available software. Commercial software and shareware should not be uploaded unless they have a copyright expressly stating that this is allowed. This includes ssh, pgp, etc.

Sample spec File

The following is part of the spec file for the "fileutils" package. It is setup to build on both the Alpha and the Intel.

Summary: GNU File Utilities
Name: fileutils
Version: 3.16
Release: 1
Copyright: GPL
Group: Utilities/File
Source0: prep.ai.mit.edu:/pub/gnu/fileutils-3.16.tar.gz
Source1: DIR_COLORS
Patch: fileutils-3.16-mktime.patch

%description
These are the GNU file management utilities.  It includes programs
to copy, move, list, etc, files.

The ls program in this package now incorporates color ls!

%prep
%setup

%ifarch alpha
%patch -p1
autoconf
%endif
%build
configure --prefix=/usr --exec-prefix=/
make CFLAGS="$RPM_OPT_FLAGS" LDFLAGS=-s

%install
rm -f /usr/info/fileutils*
make install
gzip -9nf /usr/info/fileutils*

.
.
.

      

Optflags

In this example, you see how the "optflags" directive is used from the /etc/rpmrc. Depending on which architecture you are building on, the proper value is given to RPM_OPT_FLAGS. You must patch the Makefile for your package to use this variable in place of the normal directives you might use (like -m486 and -O2). You can get a better feel for what needs to be done by installing this source package and then unpacking the source and examine the Makefile. Then look at the patch for the Makefile and see what changes must be made.

Macros

The %ifarch macro is very important to all of this. Most times you will need to make a patch or two that is specific to one architecture only. In this case, RPM will allow you to apply that patch to just one architecture only.

In the above example, fileutils has a patch for 64 bit machines. Obviously, this should only be applied on the Alpha at the moment. So, we add an %ifarch macro around the 64 bit patch like so:

%ifarch axp
%patch1 -p1
%endif
      

This will insure that the patch is not applied on any architecture except the alpha.

Excluding Architectures from Packages

So that you can maintain source RPMs in one directory for all platforms, we have implemented the ability to "exclude" packages from being built on certain architectures. This is so you can still do things like

rpm --rebuild /usr/src/SRPMS/*.rpm
      

and have the right packages build. If you haven't yet ported an application to a certain platform, all you have to do is add a line like:

ExcludeArch: alpha
      

to the header of the spec file of the source package. Then rebuild the package on the platform that it does build on. You'll then have a source package that builds on an Intel and can easily be skipped on an Alpha.

Finishing Up

Using RPM to make multi-architectural packages is usually easier to do than getting the package itself to build both places. As more of the hard packages get built this is getting much easier, however. As always, the best help when you get stuck building an RPM is to look a similar source package.